Daily Practice Problems
Class 11 Physics
Laws of Motion Question 1.

State Newton’s three laws of motion.

Question 2.

Give an expression for Newton’s second law of motion.

Question 3.

What do you understand by Impulse?

Question 4.

Give symbol, units and dimensions for static and kinetic friction.

Question 5.

What do you understand by friction?

Question 6.

A stone of mass 0.50 kg tied to the end of a string is whirled round in a circle of radius 2.0 m with a speed of 30 rev/min in a horizontal plane. What is the tension in the string? What is the maximum speed with which the stone can be whirled around if the string can withstand a maximum tension of 300N?

Question 7.

A batsman deflects a ball by an angle of 300 without changing its initial speed which is equal to 72 km/h. What is the impulse imparted to the ball? (Mass of the ball 0.20 kg).

Question 8.

Eight five-rupee coins are put on top of each other on a table. Each coin has a mass m. Give the magnitude and direction of

1. The force on the fifth coin (counted from the bottom) due to all the coins on its top,
2. The reaction of the 4th coin on the 5th coin.

Question 9.

A shell of mass 0.025 kg is fired by a gun of mass 200 kg. If the muzzle speed of the shell is 75 m/s. What is the recoil speed of the gun?

Question 10.

Two masses 5 kg and 10 kg are connected at the two ends of a light inextensible string that goes over a frictionless pulley. Find the acceleration of the masses, and the tension in the string when the masses are released.

Question 11.

A truck starts from rest and accelerates uniformly at 3.0 m/s2. At t = 12 s, a stone is dropped by a girl standing on the top of the truck (8m high from the ground). What are the (a) velocity, and (b) acceleration of the stone at t = 13s.

Question 12.

A constant retarding force of 40N is applied to a body of mass 15 kg moving initially with a speed of 10 m/s. How long does the body take to stop?

Question 13.

Give the statement for “Law of conservation of Momentum”.

Question 14.

A circular racetrack of radius 500m is banked at an angle of 22.50 . If the coefficient of friction between the wheels of a race-car and the road is 0.15. What is the, (a) optimum speed of the race-car to avoid wear and tear on its tyres, and (b) maximum permissible speed to avoid slipping?

Question 15.

Determine the maximum acceleration of the train in which a box lying on its floor will remain stationary, given that the co-efficient of static friction between the box and the train’s floor is 0.2.

Question 16.

What is the unit and dimension of “Impulse”?

Question 17.

Give the magnitude and direction of the net force acting on a stone of mass 0.5 kg.

1. Just after it is dropped from the window of a stationary car.
2. Just after it is dropped from the window of a car accelerating with 2 m/s2.

Question 18.

Two billiard balls each of mass 0.08 kg moving in opposite directions with speed 5 m/s collide and rebound with the same speed. What is the impulse imparted to each ball due to the other?

Question 19.

A stream of water flowing horizontally with a speed of 12 m/s gushes out of a tube of cross-sectional area 2×10-2 m2 and hits a vertical wall nearby. What is the force exerted on the wall by the impart of water, assuming it does not rebound?

Question 20.

A bob of mass 0.2 kg hung from the ceiling of a room by a string 4 m long is set into oscillation. The speed of the bob at its mean position is 1.5 m/s. What is the trajectory of the bob if the string is cut, when the bob is (a) at one of its extreme positions, and (b) at its mean position?

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